The present invention pertains to an improvement in the application of solid coating compositions which may be transferred to a substrate under the action of heat and pressure.
It is known to undertake transfer of solid coating compositions comprised of various combinations of resins to a substrate by cross-linking these combinations of resins under the action of heat and pressure in an acid or alkaline medium. For example, it is possible to effect the cross-linking of various combinations of resins which are able to be applied when hot, when the composition to be cross-linked comprises functional groups such as hydroxyls, ethoxy, amino, amido, carboxyls or which may contain cross-linking groups which are blocked or deactivated by substitution, such as methoxy-methyl groups, for example, as described in French Patent No. 1,568,171, or ethoxy-methyl groups or the like in an acid medium. The temperature which is required, however, must be quite high, at least 140.degree. C, and this frequently causes the degradation of some of the components. The only method which is carried out at relatively low temperature is that described in French Patent No. 1,520,562, example 2, 3 and 4. However, the compositions used therein have the drawback of only being usable for a limited period of time, i.e. the composition must be used within 24 to 48 hours after the addition of the acid catalyst and, furthermore, it cannot be used after the evaporation of the solvents. Moreover, in some instances, the catalyst reacts with certain materials, such as textile materials and coloring agents. Also, the minimum thickness of the coating must be 15 microns.